You may want to have a look at LACD kit with gate carabiners which have a safety release on the back. You could get one from German Amazon:
http://www.amazon.de/LACD-Damen-Herren-Klettersteigset/dp/B00L3B0DIY
It's easy to operate with one hand holding at the base of carabiner. I don't know if my hands are as small as your's partner, but they are small enough to make it difficult to find gloves of my size. Said so I find LACD easy to operate.
Going for smaller carabiners may be a bad idea because wires sometimes are very thick. Last thing you want to discover is it can't be clipped due to small opening..
Post edited at 14:24