Hopefully i can help..
The noise your hearing will most likly be from the Power steering pump driven off your auxillary belt at the left hand side of the engine.this will be the area to that you will need to check around and too follow the lines from it carefully checking all the way towards your steering rack and check for leaks there too.and at either side of the steering gaitors..the grinding noise as suggested above will be the lack of fluid in the pump due to your leak..and will only stop once the leak has been rectified wether this be replacing the pump itself due to it leaking / steering rack if leaking or one of the fluid lines if leaking to,so again locating the leak would be the best step to take next to find out what will need done..
There are few addtives on the market that may help depending on the size of the leak of course.But very small leaks or weeping..then you can use for example:- Lucas Power Steering Stop Leak which most local diy motor factor should sell and add that to the system and see if that helps.. ..
It would most likly depend how far away you are from your home..if you are quite far away then you do have that option of towing it in instead if you are with a breakdown company ie: AA/RAC and the like as the pump could completely fail or seize up and allow the auxillary belt to come off or snap and this will no doubt cause problems in regards to the alternator not charging and water pump not turning neither to stop the engine overheating as all these inc the PS pump are run off the same belt..if not to far from your home or quite near then just keep it topped up if possible till you manage to get it home.though the steering will be heavier to operate and then once home then see if you can locate the source of the leak..
It must quite large leak could also actually be apart from the other 3 possibles from the reservior itself either cracked or the pipe from it.might be worth checking that and see if its still attached..failling that to not cause any further damage to the rest of the system due to lack of fluid and proper lubrication internally in regards to rack or pump it might be worth actually getting towed instead...