Woocommerce Backend Search by Title and SKU

Please try this code

function search_by_sku( $search, &$query_vars ) {
        global $wpdb, $pagenow;
         if ( 'edit.php' != $pagenow || ! is_search() || ! isset( $query_vars ->query_vars['s'] ) || 'product' != $query_vars ->query_vars['post_type'] ) {
            return $search;
        }
        if(isset($query_vars->query['s']) && !empty($query_vars->query['s'])){
            $args = array(
                'posts_per_page'  => -1,
                'post_type'       => 'product',
                'meta_query' => array(
                    array(
                        'key' => '_sku',
                        'value' => $query_vars->query['s'],
                        'compare' => 'LIKE'
                    )
                )
            );
            $posts = get_posts($args);
            if(empty($posts)) return $search;
            $get_post_ids = array();
            foreach($posts as $post){
                $get_post_ids[] = $post->ID;
            }
            if(sizeof( $get_post_ids ) > 0 ) {
                    $search = str_replace( 'AND (((', "AND ((({$wpdb->posts}.ID IN (" . implode( ',', $get_post_ids ) . ")) OR (", $search);
            }
        }
        return $search;
}
add_filter( 'posts_search', 'search_by_sku', 999, 2 );