The only way I could find to do this was to search for the terms separately and then insert the results before the main result (only on page 1 though).

add_action( 'loop_start', function(){
  $searchvar = get_search_query();
  $paged = get_query_var('paged'); 
  $debug = 'search: '. $searchvar;
  // only show on seach page and only for first page of results
  if($searchvar>'' && $paged==0){
	$s = $searchvar;
	$results = array();
	$searchterms = explode(' ',$s); // "+" is removed!
	//print_r($searchterms);
	$termcount=0;
	foreach($searchterms as $searchterm){
		$debug .= '

' . $searchterm . '
--------------------------';
		$termcount++;
		$exclude_arr = array();
		${'termsfound'.$termcount} = array($searchterm);
		// search product category title
		$debug .= '

category title';
		$terms = get_terms(array(
			'taxonomy' => 'product_cat',
			'name__like' => $searchterm,
			'hide_empty' => true, // Optional 
		));
		if ( count($terms) > 0 ){
			foreach ( $terms as $term ) {
				$results[] = $term;
				$exclude_arr[] = $term->term_id;
				${'termsfound'.$termcount}[] = $term->term_taxonomy_id;
			}
			$debug .= '
excluded=' . implode(',',$exclude_arr);
			$debug .= '
terms=' . implode(',',${'termsfound'.$termcount});
		}
		// search product category description
		$debug .= '

category description';
		$exclude = implode(",", $exclude_arr);
		$terms2 = get_terms(array(
			'taxonomy' => 'product_cat',
			'description__like' => $searchterm,
			'hide_empty' => true, // Optional 
			'exclude' => $exclude,
		));
		if ( count($terms2) > 0 ){
			foreach ( $terms2 as $term2 ) {
				$results[] = $term2;  
				$exclude_arr[] = $term2->term_id;
				${'termsfound'.$termcount}[] = $term2->term_taxonomy_id;
			}
			$debug .= '
excluded=' . implode(',',$exclude_arr);
			$debug .= '
terms2=' . implode(',',${'termsfound'.$termcount});
		}
		// search product category acf description2 field
		$debug .= '

acf description2 field';
		$exclude = implode(",", $exclude_arr);
		$description2terms = get_terms(array(
			'taxonomy' => 'product_cat',
			'hide_empty' => true, 
			'exclude' => $exclude,
			'meta_query' => array(
				array(
				'key'       => 'description_2',
				'value'     => $searchterm,
				'compare'   => 'LIKE'
				),
			),
		));
		if ( count($description2terms) > 0 ){
			foreach ( $description2terms as $term3 ) {
				$results[] = $term3;  
				${'termsfound'.$termcount}[] = $term3->term_taxonomy_id;
			}
			$debug .= '
terms3=' . implode(',',${'termsfound'.$termcount});
		}
	}
	if ($termcount>1) {
		// search is AND, therefore only show results which appear in all result sets
		$commonterms = $termsfound1;
		for ($i=2; $i<=$termcount; $i++) {
			$commonterms = array_intersect($commonterms, ${'termsfound'.$i});
		}
		$commonterms = array_values($commonterms);
		if(count($commonterms) > 0){
			$debug .= '

common terms=' . implode(',',$commonterms);
			$terms3 = get_terms(array(
				'taxonomy' => 'product_cat',
				'include' => $commonterms,
			));
			foreach ( $terms3 as $term ) {
				$finalresults[] = $term;
			}
		} else {
			$finalresults = array(); // no common results
			//echo 'NOTHING!';
		}
	} else {
		$finalresults = $results; // one one term searched for
	}
	//echo '
'; echo $debug; echo '
';

	// combine results

	if ( count($finalresults) > 0 ){

		/*  [term_id] [name] [slug] [term_group] [term_taxonomy_id] [taxonomy] [description] [parent] [count] [filter] [term_order] */

		foreach ( $finalresults as $result ) {

			$thumbnail_id = get_woocommerce_term_meta( $result->term_id, 'thumbnail_id', true );

			$imageurl = wp_get_attachment_image_url( $thumbnail_id, 'swiper_news_image_size' );

			$imageurlsm = wp_get_attachment_image_url( $thumbnail_id, 'post_image_thumb' );

			//$excerpt = esc_html( $result->description );

			$excerpt = substr(esc_html( $result->description ),0,strpos(esc_html( $result->description ),' ',250));

			echo '


				


		


			' . esc_html( $result->name ) . '

		

'. $excerpt .'

					

				Read More »			
				

					
				


';

		}

	}

  }

});