As others said, just ask them. We tend to overthink these things as though there is some special code. There isn't.
A few years ago I was at Myrtle Beach for the day. Departing IFR, I picked up my clearance. When I read it back, I added, "will you be able to vector me around those storms to the north?" "That won't be a problem," was the reply.
Contacting Departure after takeoff, they vectored me west of the storms. Eventually I got an amendment to my clearance, inserting direct to a fix which would keep me away before proceeding on course.
One could be even more proactive than I was though. Look at the chart, find a fix that works, and ask for it. I'd still ask for it with CD even though they might defer until I was in the air.