如果不修改wordpress生成的主搜索查询，就没有简单的方法可以做到这一点。我想你应该posts_search &；posts_join 钩它们位于wp-includes/query.php

执行var_dump 首先查看您得到了什么&；相应修改。这里有一些未经测试的代码，我现在可以为您提供这些代码。

add_filter(\'posts_search\', \'search_function\', 10, 2);
function search_function($search, $query) {
  if(is_admin() || !$query->is_main_query() || !$query->is_search)
    return; //determine if we are modifying the right query

  global $wpdb;
  $search_term = $query->get(\'s\');
  $search = \' AND (\';

  //point 1
  $search .= "($wpdb->posts.post_content LIKE \'%$search_term%\')";

  //need to add an OR between search conditions
  $search .= " OR ";

  //point 2
  $search .= "($wpdb->comments.comment_content LIKE \'%$search_term%\')";

  //need to add an OR between search conditions
  $search .= " OR ";

  //point 3
  $search .= "($wpdb->postmeta.meta_key = \'custom_field_key\' AND $wpdb->postmeta.meta_value LIKE \'%$search_term%\')";

  //need to add an OR between search conditions
  $search .= " OR ";

  //point 4
  $search .= "({$wpdb->prefix}notes.text LIKE \'%$search_term%\')";

  //add the filter to join, sql will error out without joining the tables to the query
  add_filter(\'posts_join\', \'join_tables\');

  return $search . \') \';
}

function join_tables($join) {
  $join .= "JOIN $wpdb->comments ON ($wpdb->comments.comment_post_ID = $wpdb->posts.ID)";
  $join .= "JOIN $wpdb->postmeta ON ($wpdb->postmeta.post_ID = $wpdb->posts.ID)";
  $join .= "JOIN {$wpdb->prefix}notes ON ({$wpdb->prefix}notes.post_ID = $wpdb->posts.ID)";
  return $join;
}