Is it possible to do a grep with keywords stored in the array?

You can use some bash expansion magic to prefix each element with -e and pass each element of the array as a separate pattern. This may avoid some precedence issues where your patterns may interact badly with the | operator:

$ grep ${args[@]/#/-e } file_name

The downside to this is that you cannot have any spaces in your patterns because that will split the arguments to grep. You cannot put quotes around the above expansion, otherwise you get "-e pattern" as a single argument to grep.

args=("key1" "key2" "key3")
pat=$(echo ${args[@]}|tr " " "|")
grep -Eow "$pat" file

Or with the shell

args=("key1" "key2" "key3")
while read -r line
do
    for i in ${args[@]}
    do
        case "$line" in
            *"$i"*) echo "found: $line";;
        esac
    done
done <"file"