Get Posts by Custom Field Value

I’m using Advanced Custom Fields, and I when I use

http://example.com/api/get_posts/?post_type=CUSTOMPOSTTYPE&custom_fields=CUSTOMFIELD&CUSTOMFIELD=value

I just all the posts of that post type and the only custom field that appears is the selected field.

What I want to do is get all the posts of that post type that have the specific custom field and the specific custom field value.

Is there a way to create a controller to do this?

Thanks

https://wordpress.org/plugins/json-api/