Try
create procedure usp_GetPersonsWhoseNameContains(@LN nvarchar(50))
as
begin
select * from Person where Lastname like N'%'+@LN+'%'
end
declare @LastName nvarchar(50) = N'ی'
exec usp_GetPersonsWhoseNameContains(@LastName)
Maybe you noticed that SQL Server uses N to any quoted string input when generating DDL scripts for you.