Hi komir,
It could be done, but it's very difficult to be done correctly. Due to the internal structure of custom fields, it will make a bit slow the searches. Also, since we want to provide as easy as possible software, we can not do that with search filters, for example, should we use fulltext for fields? or is in the text search? exact one? What about number fields? Should we put a drop-down menu? a numeric slider? one radio-option or multiple selection?
So for the moment is not in our plans (mostly because of lack of resources and time), but eventually it will be done.
Thanks