Can I simultaneously use a relationship OR no relationship in an exposed filter?

TL:DR is it possible for a single exposed filter to simultaneously use a relationship OR no relationship?

A bit of background
I have a view displaying several content types which each share a "topic" field (term reference).
An exposed filter lets users filter by topic.

problem is that one such content type is actually a product reference node so it only works if the exposed filter is using a relationship - in which case, the other content types *stop* working.

I really don't want to have a second exposed filter, it needs to be just one that applies to all nodes.