What you may be looking for there is logical Or for that pair of equalities, double vertical pipe, ||
In[ ]:= Cases[Range[1, 100], x_ /; (Mod[x, 2] == 0 || Mod[x, 3] == 0)]
Out[ ]= {2, 3, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, \
26, 27, 28, 30, 32, 33, 34, 36, 38, 39, 40, 42, 44, 45, 46, 48, 50, \
51, 52, 54, 56, 57, 58, 60, 62, 63, 64, 66, 68, 69, 70, 72, 74, 75, \
76, 78, 80, 81, 82, 84, 86, 87, 88, 90, 92, 93, 94, 96, 98, 99, 100}
