Keep a single input in the RFC with char datatype. In the ABAP code get the value from this parameter and check whether the values datatype is integer or char, if its integer consider the value as emp id otherwise fname.
In the MBO, there is only single load parameter map it to the editbox in the screen. Give the edit box description as Enter empid/fname. The editbox datatype should be string, that allows interger as well as character. Hope that works.
- Midhun VP