How to add multiple category ID whlile creating multi-portfolio

Hi,

I’m creating a multi-portfolio (using Epik theme) by following tutorial:

https://appfinite.com/tutorials/how-to-setup-the-portfolio/

Everything works properly for a unique category ID. But I need to add two categories at least as parameters.

I have tried different combinations but no success:

1) Two custom fieds:
Name= query_args Value= cat=38
+
Name= query_args Value= cat=39

2) different combinations with just one custom field:

query_args cat=38&cat=39

or

query_args cat=38&39

But anyway it shows up only one category post. Never both.

Any idea?

I’ll appreciate any help.

Thanks in advance.