get_multiple_extended_posts.php

<?php
/**
 * The `get_by` method allows us to get extended post objects by field value.
 * 
 * The method expects the input array to be identical to that for `WP_Query`, and it also allows two optional custom arguments,
 * `fields` and `fields_relation` to skirt around the `$meta_query` argument
 */
$people_named_michael = Helping_Friendly_Post::get_by( array(

  'post_type' => 'person',
  'fields'    => array(
      'first_name' => 'Michael'
  )
));
 

Helping_Friendly_Post.php

<?php
/**
 * The `Helping_Friendly_Post` class is an exercise in thinking about extending the `WP_Post` class
 * 
 * @see   https://github.com/mhull/helping-friendly-plugin/blob/master/lib/class-hphp-post.php
 */

/**
 * To get a new extended post by ID
 */
$extended_post = new Helping_Friendly_Post( $post_id  );

# now we have all the post meta in the `$extended_post->fields` array
$wow = $extended_post->fields['my_meta_key'];

# ...as well as the `WP_Post` object itself (the original post we have extended)
$awesome = $extended_post->post->post_status;

/**
 * If we already have the full `WP_Post` and not just the ID, we can save a trip 
 * to the database (or the cache I suppose)
 */
global $post;
$extended_post = new Helping_Friendly_Post( $post );

$super_easy_field_value = $extended_post->fields['my_meta_key']