Include Attributes for WordPress/WooCommerce Search

functions.php

/**
 * Include Attributes for search
 * @return array|null
 */
function getProductSearchClauses() {

    /* @var WP_Query $wp_query */
    global $wp_query;
    global $wpdb;

    static $clauses = null;

    if (is_null($clauses)) {

        $s = get_query_var('s');
        $tax_query = array();
        $attributes = array(
            'my_attribute_1',
            'my_attribute_2',
            'my_attribute_3',
        );
        foreach ($attributes as $a) {

            $termIds = get_terms(array(
                'taxonomy' => $a,
                'fields' => 'tt_ids',
                'name__like' => $s,
            ));

            $tax_query[] = array(
                'taxonomy' => $a,
                'terms' => $termIds,
            );
        }

        $tax_query = array(
          'tax_query' => $tax_query,
          'cat' => null,
          'tag' => null,
        );
        $wp_query->parse_tax_query($tax_query);
        /* @var WP_Tax_Query $wp_tax_query */
        $wp_tax_query = $wp_query->tax_query;
        $relation = null;
        if ( ! empty($wp_tax_query->queries['relation'])) { // Remember the current state to revert later
            $relation = $wp_tax_query->queries['relation'];
        }
        $wp_tax_query->queries['relation'] = 'OR';
        $clauses = $wp_tax_query->get_sql($wpdb->posts, 'ID');
        if ( ! empty($relation)) $wp_tax_query->queries['relation'] = $relation; // Revert

        $clauses['where'] = preg_replace('/^ AND /', '', $clauses['where']);
    }

    return $clauses;
}
/**
 * @param string $where
 * @param WP_Query $query
 * @return string|string[]|null
 */
function my_posts_where($where, $query) {
    if ($query->is_search() && $query->is_main_query()) {
      $clauses = getProductSearchClauses();
      return preg_replace('/(\(wp_posts.post_title LIKE)/', $clauses['where'] . ' OR $1', $where);
    } else {
      return $where;
    }
}
add_filter('posts_where', 'my_posts_where', 10, 2);
/**
 * @param string $join
 * @param WP_Query $query
 * @return string
 */
function my_posts_join($join, $query) {
    if ($query->is_search() && $query->is_main_query()) {
        $clauses = getProductSearchClauses();
        $join .= $clauses['join'];
    }
    return $join;
}
add_filter('posts_join', 'my_posts_join', 10, 2);