custom fields in relevanssi's search results

<?php
/*
 * Render the_content for the my post-type
 */
add_filter('the_content', 'my_the_content');
function my_the_content($content) {

  //if the_content was triggered by relevanssi, we append the content of all relevant custom fields so that relevanssi includes their content (inlcuding the real my content if specified)
  if($post = is_the_content_called_by_relevanssi()){

    // Fields to load content from
    $fields = array('myfield1', 'myfield1');
    foreach($fields as $field){
      //pay attention to $single (http://codex.wordpress.org/Function_Reference/get_post_meta)
      //die(print_r(get_post_meta($post->ID, $field, false), TRUE));
      $content .= ' '. implode(' ', get_post_meta($post->ID, $field, TRUE));
    }
  }
  else global $post;  //in general you want to use this $post object

  return $content;
}

/*
 * Check if the_content was triggered by relevanssi
 *
 * http://wordpress.org/support/topic/snippets-not-created-from-custom-fields?replies=11#post-2168264
 */
function is_the_content_called_by_relevanssi(){
  //if relevanssi_init() does not exists, there is no relevanssi and relevanssi cannot have triggered the_contet
  if(!function_exists('relevanssi_init')) return false;

  /*
   * If we find a function call 'relevanssi_do_excerpt' in backtrace, the_content is triggered by relevanssis to create the excerpt from the_content
   *
   * expect not more than 10 the_content hooks
   * 21 calculates as follows:
   * apply_filters() + 10 * (call_user_func_array() + callbackfunction()) = 21
   * you might want to increase this. Remember it slows down you script!
   */
  //limit trace depth if php version is newer than 5.4.0
  if (strnatcmp(phpversion(),'5.4.0') >= 0)
    $trace = debug_backtrace(DEBUG_BACKTRACE_PROVIDE_OBJECT, 21);
  else
    $trace = debug_backtrace();
  //search for relevanssi_do_excerpt() in backtrace
  for($i = 0; $i<min(array(21,count($trace))); $i++){
    //if we find relevanssi_do_excerpt in the stack return the $post object, which we need
    if('relevanssi_do_excerpt' == $trace[$i]['function']) return $trace[$i]['args'][0];
  }
  return FALSE; //nothing found
}