Job is going to remain steadfast in this speech with two main points: I am righteous, and God, who is sovereign, does as He pleases.
As Job 16 begins, Job lets the friends know how terribly disappointed he is in them. They are troublesome comforters (16:2)! Job states that if their roles were reversed, he would not do to them what they are doing to him. Essentially, Job accuses them of not trying to understand. They may have come to sympathize, but they've done a very poor job (after their initial week of silence).
In 16:6ff, Job acknowledges that he is under the power of God, and it is God who has struck him down. This is the difficult part for him, the fact that it seems God is treating him as an enemy! Job's lost relationship with God is the most troubling aspect of the entire situation for him.
He vividly describes God's treatment of him with several metaphors. Job views God's actions toward him as a wild beast, an adversary, a traitor, a wrestler, an archer, and a warrior (cf. 16:9-14).
And what is Job's response to what has happened to him? "I have sewn sackcloth over my skin, and laid my head in the dust" (Job 16:15). This verse beautifully demonstrates Job's response to God's treatment. He has taken on the actions of a mourner and thrown himself at the mercy of God. He has not cursed God for his fate.
"My face is flushed from weeping, and on my eyelids is the shadow of death; although no violence is in my hands, and my prayer is pure" (16:16,17). Job continues to maintain his innocence. Let it be noted that his pitiful state has led him to weeping, but it has not led him to penitence (with sacrifices for sin, etc.). Why not? Because he knows of no sins for which he needs to offer sacrifices! Job knows the difference between righteousness and wickedness. When Job approaches God in prayer, he knows he is pure.
As Chapter 16 closes, Job again wants an audience with God. He wants the truth about his circumstances to be known. As the next chapter begins, Job states - "My spirit is broken, my days are extinguished, the grave is ready for me" (Job 17:1). He again reiterates the theme that he wants to die.
17:4,5 seems to convey that Job is genuinely concerned for his friends. He believes God has hidden the truth from them somehow, and he knows that God will not exalt them, consequently.
Job has lost the respect of the townspeople. This once honored and respected man has seen his reputation plunge to the point where people dishonor him by spitting at him (cf. 17:6).
Job's tears are so continual that he cannot see clearly, and his body has wasted away to nothing but a shadow. The friends ought to be shocked and appalled that this could happen to a righteous man. Job continues maintaining his innocence - "he who has clean hands will be stronger and stronger" (Job 17:9). But, the friends don't get it. He wishes they would open their minds to other possible causes for his suffering. Job clings to his innocence because he knows of nothing for which to repent! His friends view him as stubborn and rebellious.