我找到了一个解决方案，允许我在搜索标题和内容的同时按标签和类别搜索帖子。这正是我想要的。

信用证：https://rfmeier.net/include-category-and-post-tag-names-in-the-wordpress-search/

add_filter( \'posts_join\', \'search_join\', 10, 2 );
/**
 * Joins the terms, term_relationship, and term_taxonomy tables.
 *
 * @global $wpdb
 *
 * @param string $join The sql JOIN clause.
 * @param object $query The current WP_Query instance.
 *
 * @return string $join
 */
function search_join( $join, $query ) {

    global $wpdb;

    if ( is_main_query() && is_search() ) {

        $join .= "
        LEFT JOIN
        (
            {$wpdb->term_relationships}
            INNER JOIN
                {$wpdb->term_taxonomy} ON {$wpdb->term_taxonomy}.term_taxonomy_id = {$wpdb->term_relationships}.term_taxonomy_id
            INNER JOIN
                {$wpdb->terms} ON {$wpdb->terms}.term_id = {$wpdb->term_taxonomy}.term_id
        )
        ON {$wpdb->posts}.ID = {$wpdb->term_relationships}.object_id ";

    }

    return $join;

}

add_filter( \'posts_where\', \'custom_posts_where\', 10, 2 );
/**
 * Callback for WordPress \'posts_where\' filter.
 *
 * Modify the where clause to include searches against a WordPress taxonomy.
 *
 * @global $wpdb
 *
 * @param string $where The where clause.
 * @param WP_Query $query The current WP_Query.
 *
 * @return string The where clause.
 */
function custom_posts_where( $where, $query ) {

    global $wpdb;

    if ( is_main_query() && is_search() ) {

        // get additional where clause for the user
        $user_where = custom_get_user_posts_where();

        $where .= " OR (
                        {$wpdb->term_taxonomy}.taxonomy IN( \'category\', \'post_tag\' )
                        AND
                        {$wpdb->terms}.name LIKE \'%" . esc_sql( get_query_var( \'s\' ) ) . "%\'
                        {$user_where}
                    )";

    }

    return $where;

}

function custom_get_user_posts_where() {

  global $wpdb;

  $user_id = get_current_user_id();
  $sql     = \'\';
  $status  = array( "\'publish\'" );

  if ( $user_id ) {

      $status[] = "\'private\'";

      $sql .= " AND {$wpdb->posts}.post_author = {$user_id}";

  }

  $sql .= " AND {$wpdb->posts}.post_status IN( " . implode( \',\', $status ) . " ) ";

  return $sql;

}

add_filter( \'posts_groupby\', \'custom_posts_groupby\', 10, 2 );
/**
 * Callback for WordPress \'posts_groupby\' filter.
 *
 * Set the GROUP BY clause to post IDs.
 *
 * @global $wpdb 
 *
 * @param string $groupby The GROUPBY caluse.
 * @param WP_Query $query The current WP_Query object.
 *
 * @return string The GROUPBY clause.
 */
function custom_posts_groupby( $groupby, $query ) {

  global $wpdb;

  if ( is_main_query() && is_search() ) {
      $groupby = "{$wpdb->posts}.ID";
  }

  return $groupby;

}