If a person suffers from an incontinence, due to which drops of urine come out continuously, or he is not in a position to control his bowels, he should act as follows:
A) If he is sure that at some time during the prayer time, there will be a respite during which there will be a restraint, then he should perform Wudhu and offer prayer at such time. If during the restraint, he can control his urine or excretion only for performing Wajib acts of prayer, then he should perform only obligatory acts, and abandon the Mustahab acts (e.g. Adhan, Iqamah, Qunut etc).
B) If he has no respite and urine comes of him, the first Wudhu is sufficient. If he discharges urine or excretion once, or several times during prayer, and there is a continued incontinence, allowing no period of restraint for Wudhu, or even a part of prayer, then one Wudhu for every prayer will undoubtedly be enough except when one urinates or defecates voluntarily in which case the Wudhu becomes invalid.[i] 
If the time of restraint is just enough to allow Wudhu and a part of prayer, and if it is not painful or difficult for him to make Wudhu after each incident, he should keep a container by his side, make Wudhu every time he discharges, and continue offering the rest of prayer.[ii] In case, it is difficult for him to make Wudhu after she discharges urine, he must make Wudhu for every prayer.[iii]
One who is suffering from incontinence due to which he cannot control his bowel and feces come out intermittently, he should perform the forgotten Sajdah and Tashahhud and the Ihtiyat (precautionary) prayer immediately after completing the prayer in which case it is not necessary to renew Wudhu.[iv]
Note: This answer has been provided in accordance with the verdict of late Imam Khomeini (ra). In case you are following a different Mujtahid, you should let us know your Mujtahid's name so that an answer should be prepared in accord with his verdict.

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