Solution depends: If there aren't too many fields you want to update, I think it can be done in one query, but you will need criteria for each field, otherwise the update will propagate through all records of a field. This means you will need a criteria row in the design grid for each field - you cannot put them all on the same row. You only show 6 fields, but maybe you haven't said there are 66. Also, are the numbers text or numbers?
Assuming they are numbers and you want to always add 6 (or is that a coincidence of your post?) then this will update each field that meets the criteria by adding six to the value in the row where the field is Val(n).
Code:
UPDATE [tblYourTable] SET [tblYourTable].Val1 = [Val1]+6, [tblYourTable].Val2 = [val2]+6, [tblYourTable].val3 = [val3]+6
WHERE ((([tblYourTable].Val1)=1)) OR ((([tblYourTable].Val2)=2)) OR ((([tblYourTable].val3)=3));
Note: two great answers posted before I was finished, otherwise, I probably would have bowed out. I totally missed the point that the values were in one field. I'll leave the answer in case it could be useful to somebody, sometime, in a galaxy far, far away...