replacing a half wall with steel header
hard to say without a sketch or photo, but this sounds like a question that gets asked here a lot. the usual answers contain at least a few "depends on what is above this area", or "get an engineer on site", etc. you can put your whole house on a steel beam, sure. the questions are "how big of a beam?"; "is the foundation ready for posts to bear weight?"; and a few others. i'd suggest doing a quick search here for "bearing wall removal", and topics like that. imo, this is not necessarily a diy job, at least not without an engineer to run some numbers. good luck, and i hope the deal works out well for you.