Why can't you eat 6 meals per day? If you have a job that doesn't allow for many breaks, I would alternate whole food meals and shakes to get your 6 meals each day.
Frequent small meals throughout the day is always way better then less frequent bigger meals. It leads to more stable blood sugar levels and a constant trickling of amino acids in your blood stream. This makes for a more favourable fat burning and muscle building environment.
What I would do is buy a good whey isolate like wheytobuildmuscle from n2bm.com and add oatmeal, a scoop of greens powder and some natural almond butter to the shake. I would eat breakfast, lunch and dinner and then drink those shakes in between those 3 meals.