content search webpart query string filter with multiple values

I'm using a standard content search webpart. In my query I have a query string filter on a field called HRPortalRole. The column that links to the HRPortalRole managed property is a choice column. The querystring filter in the query looks like this.

HRPortalRole:{QueryString.role}

If I specify only one value in the query string it is working correct. (sample below)

?role=employee

What I want to do is specify more than one role, so that I can show content of both roles. For example something like this

?role=employee&role=manager

or something like this

?role=employee;manager

Is this somehow possible?