[kurapica.igas]

You can use gsub to do the replacement

line = 'frame1 and frame2 or frame3'
 
 
local keywords = {
    ["and"] = "and",
    ["or"] = "or",
}
 
print(line:gsub("[_%w]+", function(word)
    return keywords[word] or string.format("_G[%q]", word)
end))