HubDB filters always AND together the parameters. There's currently no way to do an OR. You can work around this by structuring your data differently or you can make two queries and combine the results, making sure to remove any duplicates by id.
@boulter - has there been any updates to HubDB to use OR filters? Also, is there anywhere with more in-depth documentation on what is available to use with HubDB? Currently I am unable to find anything that goes into any real detail.