I would like to request you, as a manager, to either have someone fix the problem with the microwave or simply replace it.

have 在这里是使役动词，表示"让某人做某事"的用法。 someone 是不定代词，指"某个人"，在这里指代需要被指派来修理的人。 fix 是动词，意思是"修理、修复"。 have someone fix 是一个使役动词结构，表示"让某人修理"，即"请人修理"的意思。