For that budget you will not find a gaming laptop, a decent gaming laptop will cost you at least $1000, maybe $800 if you can find some special deal on older laptops.
For that money your best bet would be to try and find a used laptop. CSGO doesn't have heavy system requirements so a laptop with a gtx 960 or so would be fine. For streaming and other programs you would need a decent multi-core CPU, a mobile i7 would be decent.
Even so, $400 for these specs on a used laptop would not likely be enough. You could try to find an AMD A10 or A8 equipped laptop, which you might find new within your budget.