kya mangne ka hai?

In the Arabian Peninsula we have a large number of non-native Hindi/Urdu speakers who regularly use a Khaleeji pidginized Hindustani to communicate in a multi-lingual, multi-national setting. One feature of this is asking someone what they want by using "mangna" instead of "chahna" or "chahiye." They also say mangna instead of "hona chahiye" for "should (be)".

Tum choTa size mangta hai? = Kya aap ko chota size chahiye?

or hona chahiye:

Pyaaj bareek bareek kaaTna mangta hai. = Pyaaz bahut bareek kaaTna chahiye.

Where is this mangna usage coming from? I recall hearing something similar in a Bollywood film, paired with the hero saying "apun ka" (which, by the way, is not used in the Khaleeji pidgin) as an affectation of Bombay street language. Has the mangne ka hai transplanted itself here from the Bombay street language? Or has this developed organically here in the Khaleej? 

I am not sure from where it has come from, but it is true that one can hear it in Mumbai a lot. I have heard it from Marathis, Gujaratis, or Christians, and a friend says he mostly hears it from Pathans in Hindi movies. If I get to know more on the origin of this practice, I shall let you know.

Also, please don't call it "street language". Some very well educated people also speak like this :)