I have a report where i need to add the condition in left outer join

left outer join t1.c1 = t2.c1 and t2.c2 = '100' and t2.c3 = 50

Can someone help me on this.
Please don't say that try to add the query in command, I know that will work but what i want is how to add this in the design so that the report can be made generic and user will have the capability to modify the where clause.

Thanks in advance

Bala