Nhibernate CreateCriteria wildcard Like when

In SQL I can write

SELECT blah FROM Clients
Where @p1 Like '%'+lastname+'%'

How do I represent this with CreateCriteria in Nhibernate?

I've tried s.CreateCriteria<Client>.Add(Restrictions.Where<Client>(c => "something".Contains(c.LastName))

but get an error

System.Exception: Unrecognised method call: System.String:Boolean Contains(System.String)\r\n at NHibernate.Impl.ExpressionProcessor.ProcessCustomMethodCall(MethodCallExpression methodCallExpression)

I've also tried

s.CreateCriteria<Client>.Add(Restrictions.Where<Client>(c => "something".IndexOf(c.LastName) != -1))

but get

"variable 'c' of type 'TrinityFinance.Data.Entities.Client' referenced from scope '', but it is not defined"

Note the order is important here.

@p1 Like '%'+lastname+'%'

is not the same as

lastname Like '%'+@p1+'%'