这是我的密码。真奇怪！如果我将任何静态值替换为$s\\u字符串，它就可以正常工作。提前感谢您的帮助。

$s_string = !empty($_GET[\'q\']) ? sanitize_text_field($_GET[\'q\']) : \'\';
$custom_fields = new WP_Query(array(
            \'post_type\' => \'post_type\',
            \'posts_per_page\' => -1,
            \'post_status\' => \'publish\',
        ));
        $fields = $custom_fields->posts;
        $post_ids = array();
        foreach ($fields as $post) {
            $post_ids[] = $post->ID;

        }
        if( count( $post_ids ) > 1 ) {

            $sub_meta_queries = array();

            foreach( $post_ids as $value ) {

                $sub_meta_queries[] = array(
                    \'key\'       => $value,
                    \'value\'     =>  $s_string,
                    \'compare\'   => \'LIKE\'
                );

            }

            $meta_queries[] = array_merge( array( \'relation\' => \'OR\' ), $sub_meta_queries );

        } else {

            $meta_queries[] = array(
                \'key\'       => $post_ids,
                \'value\'     => sanitize_text_field( $s_string ),
                \'compare\'   => \'LIKE\'
            );
        }