bash - how to combine 2 grep checks in a while loop -

What I'm trying to do by default:

  while string1 exists Echo is present in Foo.log or in string 2 foo.log. Examples of input files:  
 It should be kept while running  
  string1 foo bar string2   
  foo bar < / Code>  
 This time should be stopped  
  Foo bar string1  
 = "post-text" itemprop = "text"> 
 "String1 is not present in foo.log or exists in string 2" in foo.log " 
  while! Grep -q "string1" foo.log || Grep -q "string2" foo.log; Echo done