Hi,
Use the FINDSTRING() function -- the Alteryx help on this is quite good. It returns the starting position of the text you are finding or a -1 if the term is not found. It is case sensitive, so in your example in a Filter tool, the syntax would be:
FINDSTRING([Field2],"AbC")
You could also combine them (in a Filter tool) to get both AbC and SB with this syntax:
FINDSTRING([Field2],"AbC")!=-1 && FINDSTRING([Field2],"SB")!=-1
I hope this helps