Just to clarify, you’re wanting the standard WordPress search to be able to lookup the values in custom fields? Since MasterPress stores values in post meta, a plugin like Search Everything will allow this to partially work. http://wordpress.org/plugins/search-everything/
But I agree, it would be good to have more specific support for this too. Thanks for the suggestion.
MasterPress 1.1.6 is now availale. This release is a minor release, containing a new option for Related Post fields. You are now able to select what post statuses should be available in the related post field.
MasterPress requires a minimum of WordPress version 4.9, MySQL 5.6, and PHP version 5.6.20.
We also recommend that PHP is configured to use a memory limit of 64MB per request (128MB may be required for sites with higher complexity).
This plug-in is not compatible with the WordPress.com hosted service.