PL/SQL :: Merge Statement - Update Only When There Is Difference?

I have two tables have almost the same columns, how can I use merge statement to update the target table only when there is difference between source and target table. Is there any easier way not compare each column one by one? I am using Oracle 11.2

Here is the MERGE statement:

Merge into tb_trgt trgt using tb_src src
on (src.id = trgt.id)
when not matched then insert (trgt.id, trgt.nm, trgt.addr) values (src.id, src.nm, src.nm)
when matched then update set trgt.nm = src.nm, trgt.addr = src.addr
where trgt.nm <> src.nm or trgt.addr <> src.addr
;

Is there any easier way to specify the where clause in the NOT MATCHED? I don't want compare each column of the tables. Since I may have many columns in the tables.