How to use Like Operator with (%) in MyBatis?

[v.sk]

I want to achieve Select * from patient where last_name like '%john%' with mybatis 3.0.

I am using the following code but somehow doesn't seam to work as expected and gets all the records.
select * from patient where last_name like '%'|| #{lastName} ||'%'.

Anyone aware of the solution?

Regards,
Sk