Clement's death record stated that he was married:
"Texas Deaths, 1890-1976," database with images, FamilySearch (https://familysearch.org/pal:/MM9.3.1/TH-1942-25240-114620-87?cc=1983324 : accessed 10 June 2016), Death certificates > 1966 > Vol 157, certificates 078001-078500, Dec, Bexar-Callahan counties > image 195 of 509; State Registrar Office, Austin.
but still it is not clear to whom.
I don't now, if it will works in US, but maybe you can search church records? At least in Europe, in such records are often notes about current/previous marriages, children etc. Clement was born in Panna Maria, small community of Polish immigrants, so very likely he was a catholic. There is only one parish: http://www.pannamariatexas.com/ImmaculateConceptionChurch.htm
And again, as he died and was buried in San Antonio, you could check nearby parishes (especially that with Polish communities). This will narrow search down.