title: Retrieve posts by custom field with WP-REST-API in Javascript
body: <p>What is the right URL to retrieve posts by meta_query with the WP-REST-API?</p>
  
  <p>The custom field I want to use can contain multiple values, I tried this for custom field which only can contain a single value and this works. </p>
  
  <p>wp-json/posts?format=json&amp;filter[meta_key]=content_type&amp;filter[meta_value]=2</p>
  
  <p>But I can't get it work with a custom field which can contain multiple values (array/object). Anyone?</p>