摘自Wordpress参考：

https://developer.wordpress.org/reference/hooks/posts_search/#user-contributed-notes

您可以通过以下方式仅按帖子标题进行搜索：

function __search_by_title_only( $search, $wp_query )
{
    global $wpdb;
    if(empty($search)) {
        return $search; // skip processing - no search term in query
    }
    $q = $wp_query->query_vars;
    $n = !empty($q[\'exact\']) ? \'\' : \'%\';
    $search =
    $searchand = \'\';
    foreach ((array)$q[\'search_terms\'] as $term) {
        $term = esc_sql($wpdb->esc_like($term));
        $search .= "{$searchand}($wpdb->posts.post_title LIKE \'{$n}{$term}{$n}\')";
        $searchand = \' AND \';
    }
    if (!empty($search)) {
        $search = " AND ({$search}) ";
        if (!is_user_logged_in())
            $search .= " AND ($wpdb->posts.post_password = \'\') ";
    }
    return $search;
}
add_filter(\'posts_search\', \'__search_by_title_only\', 500, 2);

如果您只想通过发布内容进行搜索，您可以稍微更改上述内容，然后执行以下操作：

        $search .= "{$searchand}($wpdb->posts.post_content LIKE \'{$n}{$term}{$n}\')";