Many other people have mentioned the need to search for custom fields. The advanced option doesn’t look like it is available in Android. I would ask at the least that it is added to the Android App. But honestly it would be much better to just search in the general search instead of having to do an advanced option.
It would also be helpful to have the search highlight and take us to the location of the searched item. The details come up, but when closing the details it would be nice to see the item highlighted for a time on the main window.