Filtering with OR instead of AND

Is there any way to apply multiple filters and have content satisfying any of the filters (not all) appear. In other words, is there any way for the query to connect each filter with an OR instead of an AND?

For mine the query is:
WHERE (users_roles_value_0.rid = 3) AND (node.nid = 10)

And I want it to be this:
WHERE (users_roles_value_0.rid = 3) OR (node.nid = 10)

I would also like to know if more complicated boolean operations are possible but being able to use OR would be a big step forward for me.

Thanks!