So you can do
$meta_values = get_post_meta( $post_id, $key, $single ); to grab the meta values from a post..
But how do you use $meta_values to apply them to another post? I'm not sure how you use $meta_values in add_post_meta. I am trying to copy all the custom fields from one post_id, and applying them to another post_id.
I should mention that the post that is getting a copy of the custom fields is a custom post type, and the source post is a regular post.