You won't find one with that focal range as it's never been made. A lens with such a range will have far too many optical compromises and will be bulky and heavy, so it's unlikely to ever be made without a major change in materials technology. In 35mm terms, you're after an equivalent 28-400mm lens, and no manufacturer has ever come anywhere close to achieving that on any SLR system. In APS-C terms the equivalent would be an approximate 18-250mm which has been achieved by Tamron/Sigma, but the lens has to be used at modest apertures to achieve acceptable sharpness and exhibits very obvious barrel distortion at the wide angle end and pincushioning at the telephoto end. It's a lens which makes no sense at all as there are better performing digital bridge cameras which are smaller and lighter which can produce an overall similar image quality.
You can only achieve the focal angle you're after by using two micro four thirds zoom lenses or via two regular four thirds models with a four thirds to micro four thirds adaptor. Using micro four thirds models only, you could do this using the 14-45mm and 45-200mm lenses, both by Panasonic.
At the present time, the closest single micro four thirds lenses to what you want are the Olympus 14-150mm and the Panasonic 45-200mm. The first lens has a wide angle to medium telephoto capability, the second has a short telephoto to long telephoto capability.
I suggest that you click here
to look at the micro four thirds joint catalog to see what's available.
Sorry you won't find precisely what you want, but I hope that my reply has saved you wasting further time in searching. Please take a moment to rate my answer.