How do i become a quant?

I'm looking at eventually becoming a quant. I know that to be a quant that gets hired by investment banks and hedge funds, I'd need a Phd (maybe MSc) in some highly quantitative field like; Physics, Mathematics or Financial engineering. My question is, would employers hold a Phd in Economics or Econometrics in the same regard?

If not, what would it take to get into a Financial mathematics or Financial computing postgrad program? Most university prospectuses say they require candidates to have had a first degree in (again) some highly quantitative field. Occasionally, they list economics as one of those fields, but otherwise they're pretty vague and that's not helpful to me. In general would a BSc in Economics or Economics & Econometrics be sufficient to get into one of those postgrad programs?