leaves on runner beans poorly

Could be some sort of virus disease or simply a developmental (growth) problem caused by irregular watering or wet/dry alternation. I don't think beans suffer particularly from virus diseases. As long as the majority of leaves are healthy and the new ones forming are ok then just ignore it. Most of your beans will be formed on the higher parts of the bean plant anyway.

Only time I've seen something like this was on a vine, and it was caused by Vine Erinose Mite. With this, you usually find creamy-white hairy patches which turn brown on the underside of the leaves. Inside that live tiny, microscopic mites. They're a kind of gall insect, and I wouldn't worry about them, unless it attacks every single leaf, your beans can afford to sacrifice a few leaves.