You wrap in parenthesis like so:
([artist]="Bob Dylan" or [artist]=Neil Young")When using the wizard to construct your search, you can hover the mouse just to the left of the first rule to be "or'd" and you will see the cursor change to a "clicky hand", click there to get at an opening parenthesis, then do the same, just to right of the last rule to "or'd" to get the closing partner.
You can see the dev post on the subject
Here.
-marko